The present invention relates to a context providing method, system, and apparatus for acquiring or generating a context satisfying a request representing the context representing a situation for a user, article, environment, or the like, and sending a context notification.
Conventionally, a computer system has been proposed, which generates context information representing a context requested from an application and transferring the context information to the application via a network. Japanese Patent Laid-Open No. 2001-216315 (reference 1) discloses the following method of generating and providing context information having a high degree of satisfaction for a user.
(1) At least one context data unit information made up of identification information of one context data used for generating context information and at least one attribute information for designating a feature of the context data is made to correspond to identification information of the context information and registered in an information-data unit correspondence table in advance,
(2) the context data unit information is made to correspond to a context data source suitable for acquiring context data identified by the identification information of the context data unit information and registered in a data unit-source correspondence table,
(3) at least one context data unit information having context data of a feature suitable for generating context information associated with a management target requested from an application is specified by looking up the information-data unit correspondence table,
(4) a context data source suitable for acquiring context data identified by the identification information of the specified context data unit information is specified by looking up the data unit-source correspondence table, and
(5) context data is acquired from the specified context data source, and context information requested from the application is generated using the acquired context data and output.
The conventional context providing method described above can be summarized as follows. An attribute for a context source required for generating the requested context information is determined using the information-data unit correspondence table. A context source having the determined attribute is determined using the data unit-source correspondence table to generate and provide the context information.
The conventional context providing method, however, determines the context source from the requested context information through the context source attribute. For example, an automobile has a GPS (Global Positioning System) as a context source, and an automobile position is defined as a context. In addition, another context that a user gets in this automobile is present. In this case, a context as the user's position cannot be generated from the above two contexts.
In the conventional case, a new context cannot be disadvantageously generated from a combination of a plurality of contexts, as described above.